KR100836158B1 - Heat-curable adhesive film having good heat-resistance and workability - Google Patents

Abstract

A heat-curable adhesive film is provided to prevent the damage of a reinforcing material or flexible printed circuit board when the reinforcing material adheres to the flexible printed circuit board, and to enhance reliance and yield of a product. A heat-curable adhesive film is a laminate comprising an adhesive layer(20), a release paper(30) formed on one surface of the adhesive layer, and an exfoliative film(10) formed on the other surface of the adhesive layer. The adhesive layer comprises 100 parts by weight of acrylonitrile butadiene rubber containing a carboxyl group, 50-100 parts by weight of an epoxy resin, 1-20 parts by weight of at least one hardener selected from amine-based or acid anhydride-based hardeners, and 0.01-1 parts by weight of a silicone-based surface treatment agent. The silicone-based surface treatment agent is a polysiloxane-based or organically modified polysiloxane.

Description

Thermosetting adhesive film with excellent heat resistance and workability {HEAT-CURABLE ADHESIVE FILM HAVING GOOD HEAT-RESISTANCE AND WORKABILITY}

1 is a cross-sectional view of the adhesive film according to an embodiment of the present invention.

2 is a schematic diagram of a lamination machine according to an embodiment of the present invention;

Figure 3 is a schematic view of a hot press for bonding the thermosetting adhesive film to the reinforcing material according to an embodiment of the present invention.

The present invention relates to a thermosetting adhesive film having excellent heat resistance and workability. More particularly, the present invention relates to a reinforcing member or flexible printed circuit board because it has better heat resistance and workability than a conventional adhesive film used when attaching a reinforcing material to a flexible printed circuit board. And thermosetting adhesive film having excellent heat resistance and workability, which can prevent product damage and increase yield of products as well as product reliability due to no lifting of adhesive between flexible printed circuit board and reinforcement material under high temperature conditions. .

In recent years, in line with the development of embedded technology in electronic components and the shortening and thinning of electronic products, the demand for flexible printed circuit boards has been continuously growing. Conventionally, the method of manufacturing such a flexible printed circuit board is to dry a dry film on a copper foil laminated plate on which a copper foil is formed on a polyimide film to form a circuit pattern through an exposure, development, and etching process, and then attach a coverlay film and coverlay. The film is bonded to the outermost copper foil to produce a flexible printed circuit board.

After this process, in order to bind the external device to the edge of the flexible printed circuit board, a reinforcing material such as glass epoxy or polyimide having high heat resistance is attached, and these reinforcing materials have a thickness of 0.1 mm to 2 mm. It is common for the thickness difference from the circuit board to be quite large. When the reinforcement material is considerably thicker than the thickness of the flexible printed circuit board, there is a limit to press bonding using the roll, and it is difficult to bond due to the breakage of the reinforcement material and the flexible printed circuit board due to the high pressure when using the hot press.

Conventionally, these reinforcing materials are attached to a double-sided tape with adhesive force, but the adhesive strength is weak, and heat resistance that can withstand the heat history applied in a future process is weak, which is a reality that many thermosetting adhesive films are currently employed. Accordingly, when the base material of the reinforcing plate is a thin or soft material, the adhesive film (FIG. 2, B) and the reinforcing material (FIG. 2, C) were press-bonded to increase airtightness to improve the initial adhesion between the flexible printed circuit board and the reinforcement. When the base material of the reinforcing material is thick or hard, the punching process is applied to the shape of the reinforcing material without directly passing between the rolls and press-bonded using an iron or the like. In addition, there is a disadvantage that may damage other circuit patterns other than the reinforcement when applying a high pressure during thermal compression using a hot press after pressing. For example, using a hot press at a temperature of 140 ° C. to 170 ° C., and thermocompression bonding for 1 hour or more under a pressure condition of 20 kg / cm 2 to 60 kg / cm 2 may cause the flexible printed circuit board to be damaged or the cushioning material protecting the same. There is a problem.

In addition, since the heat resistance to withstand a high temperature of 260 ℃ or more for a certain time is required in the process of the flexible printed circuit board after bonding, when the reinforcing material is attached to the flexible printed circuit board, it shows high adhesive strength under the condition of no damage of the flexible printed circuit board. There is an urgent need to develop an adhesive film capable of maintaining its properties even at high temperature.

The present invention has been made to solve the above problems, the object of the present invention is better heat resistance and workability than the conventional adhesive film used when attaching the reinforcement to the flexible printed circuit board of the reinforcement or flexible printed circuit board In order to provide a thermosetting adhesive film having excellent heat resistance and workability, which can prevent damage and increase the yield of the product as well as the reliability of the product due to no lifting of the adhesive between the flexible printed circuit board and the reinforcement material under high temperature conditions. will be.

The thermosetting adhesive film having excellent heat resistance and workability according to the present invention for achieving the above object is an adhesive film in which a release paper is laminated on one side of the adhesive layer and the adhesive layer, and a release film is laminated on the other side of the adhesive layer, The composition of the adhesive layer is 50 to 100 parts by weight of an epoxy resin, 1 to 20 parts by weight of at least one curing agent selected from amine or acid anhydride based on 100 parts by weight of acrylonitrile butadiene rubber (NBR) containing a carboxyl group, It is characterized by including a 0.01-1 part by weight of a silicon-based surface treatment agent.

Preferably, the silicon-based surface treatment agent is a polysiloxane-based or organically modified polysiloxane, characterized in that it contains a defoaming agent to promote the rise of bubbles to the surface inside the adhesive.

More preferably, the NBR including the carboxyl group has a weight average molecular weight of 2,000 to 200,000, an acrylonitrile content of 10 to 60% by weight, and a carboxyl group content of 1 to 20% by weight.

In addition, the adhesive film is preferably a heat history is applied between the thermosetting adhesive film and the reinforcing material through the thermal compression, the adhesive force is expressed and is fully cured through the post-cure (post cure) is then raised to the thermal stimulus applied after It is characterized by the absence.

Hereinafter, the present invention will be described in detail with reference to embodiments and drawings of the present invention. These examples are only for illustrating the present invention in more detail, it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples in accordance with the gist of the present invention. .

1 is a cross-sectional view of an adhesive film according to an embodiment of the present invention, the adhesive layer 20 is formed on one side of the release paper 30 and the release paper 30, and the upper surface of the adhesive layer 20 The release film 10 is laminated.

The release film 10 according to an embodiment of the present invention has a thickness of 20 to 100 μm, preferably 30 to 60 μm, and the release film 10 may be polyethylene, polyethylene terephthalate, or polypropylene film. The thing which provided peelability with silicone resin to these can be used.

The release paper 30 of the thermosetting double-sided adhesive film according to the present invention has a thickness of 50 ~ 200㎛, preferably 100 ~ 150㎛ used which is punched to a suitable size according to the purpose used in the flexible printed circuit board (打 拔) This is because it gives proper strength for cutting and has better thermal stability than peeling film when passing adhesive film and reinforcement through heated roll when laminating. Release paper can also improve workability by using a polyethylene or silicone resin coated to give the peelability.

The adhesive constituting the adhesive layer 20 according to an embodiment of the present invention is 50 to 100 parts by weight of a polyfunctional epoxy resin based on 100 weights of acrylonitrile butadiene rubber (NBR), one selected from amine or acid anhydride. It is comprised by the composition containing 1-20 weight part of said hardening | curing agents and 0.01-1 weight part of silicone type surface treating agents.

The NBR containing the carboxyl group has a weight average molecular weight of 2,000 to 200,000, preferably 3,000 to 200,000, and has an acrylonitrile content of 10 to 60% by weight, preferably 20 to 50% by weight, and a carboxyl group content. It shall be 1 to 20 weight%. At this time, when the weight average molecular weight of NBR is lower than 2,000, the thermal stability is poor, and when it is higher than 200,000, the solubility in solvent is worsened, the viscosity increases during solution preparation, and the workability becomes poor, and the adhesive force also decreases. In addition, when the acrylonitrile content is lower than 10% by weight, the solvent solubility is lowered. When the acrylonitrile content is higher than 60% by weight, the electrical insulation is poor. And when the content rate of the carboxyl group is 1 to 20% by weight, the adhesion between NBR and other resins, and the adhesive substrate becomes easy, so that the adhesive force increases.

In addition, the epoxy resin may be added in an amount of 50 to 100 parts by weight based on 100 parts by weight of NBR, and bisphenol-A type epoxy, bisphenol F type epoxy resin, and Novolac epoxy may be used. It is preferable that the equivalent (g / eq) of is 200-1000. Preferably, the epoxy resin is characterized in that 50 to 100 parts by weight with respect to 100 parts by weight of NBR, which is less elasticity of the adhesive film in the semi-cured state when added more than the epoxy resin compared to the NBR and when the reinforcement and lamination This is because the airtightness is insufficient, the adhesive film is easily expanded due to thermal stimulation, and reinforcement and lifting may occur.

In addition, the curing agent in the composition of the adhesive may be used alone or in combination with an amine-based curing agent and an acid anhydride-based curing agent, it is preferable to use 1 to 20 parts by weight based on the NBR 100 weight.

The silicon surface treatment agent is preferably 0.01 to 1 parts by weight based on the NBR 100 weight, characterized in that the polysiloxane or organically modified polysiloxane-based having a low surface tension, and the components constituting the adhesive film and There should be incompatibilities. For example, in the case of dimethylpolysiloxane in Chemical Formula 1, the molecular weight and the chain length of the silicone are controlled to control compatibility and solubility. The higher the molecular weight, the greater the incompatibility and the lower the flowability. In addition, in the present invention, it is preferable that the role of the defoamer to promote the air bubbles to the surface inside the adhesive rather than the role of the antifoaming agent to destroy bubbles that may occur during the adhesive stirring, additionally the peeling force in the release paper and release film It is good to have slip to lower the

The adhesive layer 20 having the above composition has a viscosity of 100 to 2,000 CPS, preferably 400 to 1,500 CPS, and is applied on a release film so as to have a thickness of 25 to 50 μm after drying and 2 to 10 minutes at 50 to 200 ° C. After curing for a period of time, a release paper is laminated to obtain a thermosetting adhesive film.

In the manufacturing method, a sufficiently stirred thermosetting epoxy adhesive is transferred to a pump and applied to a base film that runs continuously in a liquid fan. The thickness of the coating liquid can be adjusted as the distance between the comma coater and the surface of the base film. have. The wet coating film applied to the surface is dried while passing through the UV zone or the dryer zone, and the plate-like processed material thus treated has a thickness of about 20 to 80 µm after drying, but preferably 25 to 50 µm. In addition, as a method of applying a coating liquid to a conventional plate-like workpiece continuously running, a gravure court method, a blade court method, a wire bar court method, and a reverse court Method, reverse roll court method, extrusion court method, slide court method, dip court method, knife court method, comma court Law). This coating method requires a uniform surface in the width direction of the plate-like object and an accuracy of the thickness after drying of the coating liquid. For example, the wet coating film according to the comma court method is to coat the coating liquid of high viscosity (200 ~ 2000CPS) with a comma blade to coat the coating amount is the solid content, viscosity of the coating liquid and the gap of the comma blade It is affected by and the like and is usually at a level of 10 to 100 g / cm 2 (after drying). This method has the advantage of easy coating of a coating liquid having a wide range of viscosities. According to the gravure court method, the amount of coating liquid to be coated depends on the size of the cells engraved on the roll and the concentration of the coating liquid, which can always maintain a constant coating thickness, unlike the comma court method. Relatively low coating liquids, low viscosity coating liquids and emulsion type coating liquids are suitable. The coating amount is 2 to 40 g / cm 2 (wet state) and 0.5 to 5 g / cm 2 (after drying). Normal gravure has a diameter φ of 200 mm or more, but smaller micro gravures of less than 100 mm have a small diameter φ, so that the rotation speed is high and there is no problem due to the back up roll. The coating method using a wire bar varies depending on the thickness of the wire wound on the wire bar, and the amount of the coating liquid varies. The coating method by the extrusion court method is a coating liquid discharged from an extruder. Is a method of treating the plate-like object. In addition, the reverse roll court method applies a coating liquid to a plate-like object by using a roll to control the thickness of the coating film. Thus, a thermosetting adhesive film is provided through various devices for coating various coating liquids. Can be prepared.

It will be described in more detail through the following examples and comparative examples.

 Example 1

To 100 parts by weight of NBR containing a carboxyl group, 50 parts by weight of bisphenol a type epoxy, 5 parts by weight of diamino diphenyl sulfone (DDS) as a curing agent, and 0.01 parts by weight of dimethylpolysiloxane (formula 1 below) were mixed as a silicone-based surface treatment agent to prepare a mixed solution. The mixed solution was dissolved in acetone and then stirred sufficiently using a high speed stirrer, coated on a release film, and dried at 160 ° C. for 5 minutes to prepare an adhesive film having a thickness of 40 μm after coating.

[Formula 1]

Example 2

Except for adding 80 parts by weight of the amount of bisphenol a epoxy in the conditions of Example 1 and the same as in Example 1.

Example 3

Except that 100 parts by weight of the bisphenol a type epoxy was added under the conditions of Example 1, it was the same as in Example 1.

 Example 4

It is the same as Example 1 except that 0.05 weight part of dimethylpolysiloxane was added on condition of Example 1.

Example 5

The same procedure as in Example 1 except that 0.5 parts by weight of dimethylpolysiloxane was added under the conditions of Example 1.

 Example 6

It is the same as Example 1 except that 1 weight part of dimethyl polysiloxane was added on condition of Example 1.

  [Comparative Example]

To 100 parts by weight of NBR containing a carboxyl group, 150 parts by weight of bisphenol a type epoxy and 5 parts by weight of diamino diphenyl sulfone (DDS) as a curing agent were added, and 1 part by weight of dimethylpolysiloxane was mixed to prepare a mixed solution, which was then dissolved in acetone. After sufficiently stirring using the coated on a release film and dried for 5 minutes at 160 ℃ to prepare an adhesive film to a thickness of 40㎛ after coating.

 Experimental Example 1

In this experiment, the adhesive films prepared in Examples and Comparative Examples of the present invention were passed between 5 rolls at a pressure of 5 kg / cm 2 at 120 ° C. and adhered to the reinforcement material under the following conditions using a hot press. After peel strength was measured, the angle between the sample and the adhesive force measuring device at this time is 180 °, the speed was 50mm / min. And the average value was obtained through 10 tests for each condition (see Table 1). At this time, the specimen was peeled off the peeling film, using a glass epoxy having a thickness of 0.5mm as a reinforcing material for the exposed adhesive film surface, passed between the heated rolls, cut into 2cm wide and 12cm long, 50mm thick poly Placed between the mid films, using a hot press, the hot plate heated to 150 ° C. was vertically lowered, and thermally pressed for 1 minute at a pressure of 40 kg / cm 2, and then immediately measured adhesive strength. All were applied. The heat resistance of the adhesive sculptures was confirmed by post-curing the specimen fabricated under the above conditions and then floating for 30 seconds in a soldering furnace at 260 ° C to lift the sample through deformation and bubbles between the reinforcing material and the adhesive film. , Good when the number of bubbles up to 1mm is less than 1 in the specimen (◎), Good when 1 ~ 2 is out (○), 3 ~ 5 is normal (△), 5 or more is bad It was set as (Х). The measurement of the peel force is to determine the degree to which the prepared thermosetting adhesive film easily falls off the release paper and the release film, which is an important factor in determining the good and bad workability in actual use. As the measuring method, the tensile strength tester mentioned above was used, and the size of the specimen was also the same, but the end of the adhesive and the peeling film peeled from the release paper without fixing the hot pressing process by hot press was fixed to the jig of the tensile strength tester. After that, the average value was obtained by pulling by the method described above. (Refer to Table 2) The higher the measured value, the more peel force is required, so workability is inferior. On the contrary, if the peel force is too low, the adhesive film is difficult to fix in release paper and release film. Peeling force is closely related to the release paper coated with polyethylene or silicone resin and the tacky, surface tension, and surface roughness of the surface of the release film and the adhesive film. Adhesive properties, workability and heat resistance were measured as the physical property measurement items, and the values are shown in Table 1 below.

Experimental Example 2

In this experiment, the specimens prepared in Examples and Comparative Examples of the present invention were thermally pressed for 1 minute through a hot press in the same manner as in Experiment 1 and subjected to post cure in a dry oven at 150 ° C. for 1 hour. After coarsening, the adhesive strength thereof was measured, that is, the adhesive strength after increasing the degree of curing, and the evaluation method of heat resistance and workability was the same as in Experimental Example 1.

Experimental Example 3

In this experiment, the specimens prepared in Examples and Comparative Examples of the present invention were thermally pressed for 1 minute through a hot press in the same manner as in Experiment 1 and subjected to post-cure for 3 hours in an oven at 150 ° C. After measuring the adhesive strength, that is, the adhesive strength after increasing the degree of curing, the evaluation method of heat resistance and workability is the same as in Experiment 1.

The values measured by the method of Experimental Example with the specimen produced by the above Examples and Comparative Examples are shown in Table 1 and Table 2 below. The unit of adhesive force and peeling force is "g _f / cm".

TABLE 1

Experimental Example 1 / Evaluation Items Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative example Adhesion 1820 1630 1410 1730 1520 1430 1200 Heat resistance ◎ ○ X ○ △ X X Experimental Example 2 / Evaluation Items Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative example Adhesion 2200 2000 1800 2050 1950 1900 1770 Heat resistance ◎ ◎ △ ◎ ○ ○ X Experimental Example 3 / Evaluation Items Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative example Adhesion 2270 2080 1930 2200 2070 1990 1900 Heat resistance ◎ ◎ △ ◎ ◎ ○ △

TABLE 2

Evaluation item Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative example Peel force 50 65 74 40 35 28 41

As can be seen in Table 1 and Table 2, Examples 1 to 3 according to the present invention, the adhesive force and the peeling force is different depending on the epoxy resin and the addition amount, the silicone-based as in Examples 4 to 6 According to the addition amount of the surface treatment agent can be seen the relationship between the adhesive force of the reinforcing material and the peeling force of the release paper, when using the thermosetting adhesive film used when attaching the reinforcing material to the flexible printed circuit board as an adhesive film according to the present invention It can be seen that the damage of the flexible printed circuit board or the reinforcement can be prevented and the reliability of the product and the yield of the product can be improved.

In the present specification, the present inventors describe only a few examples of various manufacturing and analysis experiments performed according to the manufacturing method according to the present invention, but the technical idea of the present invention is not limited thereto and is variously modified by those skilled in the art. Of course it can be implemented.

As described above, the thermosetting adhesive film having excellent heat resistance and workability according to the present invention has better heat resistance and workability than the conventional adhesive film used when attaching the reinforcing material to the flexible printed circuit board. It is possible to prevent the damage, and there is no lifting effect of the adhesive between the flexible printed circuit board and the reinforcement material under high temperature conditions, so that it is possible to increase not only the reliability of the product but also the yield of the product.

Claims (4)

delete In the thermosetting adhesive film, A release film is laminated on one side of the adhesive layer and the adhesive layer, and a release film is laminated on the other side of the adhesive layer, and the composition of the adhesive layer is 100 wt% of acrylonitrile butadiene rubber (NBR) containing carboxyl groups. 50-100 weight part of epoxy resins, 1-20 weight part of 1 or more types of hardening | curing agents selected from an amine type or an acid anhydride type, and 0.01-1 weight part of silicone type surface treating agents, The silicone-based surface treating agent is a polysiloxane-based or organically modified polysiloxane, thermosetting adhesive film. The method of claim 2, NBR containing the carboxyl group has a weight average molecular weight of 2,000 to 200,000, acrylonitrile content of 10 to 60% by weight, carboxyl group content of 1 to 20% by weight, characterized in that the thermosetting adhesive film. The method according to claim 2 or 3, The adhesive film is characterized in that the heat history is applied between the thermosetting adhesive film and the reinforcing material through thermocompression and the adhesive force is expressed, and thereafter, there is no lifting phenomenon against the thermal stimulus applied after the curing by the post cure. , Thermosetting adhesive film.

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